Pneumatic zone valve controlling heated water into coil

Jalen_Jalen2006

I know some of these photos are very rough please bear with me, I just don’t understand what any of this stuff is, this is a building and the space isn’t getting any heat. I know there’s a restrictor, I have air pressure going into my zone valve, my original diagnosis was a bad zone valve which I still think it is bad. I just don’t understand how this air handler is pneumatically controlled. On the back side of it there’s an airline going into what I believe is a transducer it says 4 psi on it then it goes into an electrical circuit which I believe is my temp sensor( I have no idea.)

I have a day and night setup, day regulator is at 15, night is at 20. I have 15 psi at 60 degrees at my thermostats. I actuate it and I bleed off all my pressure I go to the air handler, nothing happens. Once again it could just be a bad zone valve.

mattmia2

My limited knowledge guess would be the electrical device is just a pneumatic switch that turns the blower on when it sees pressure and all the logic is pneumatic.

mattmia2

is there pressure or not pressure at the valve? is it hot on both sides in one f those conditions? commercial valves being normally open is common.

ratio

First, see if you can open the valve manually. If it's NO, pulling the air supply will open it. If it's NC, you'll need a li'l squeeze bulb & gauge to open it. (see https://www.uri.com/controls-and-electrical/pneumatic/accessories/squeeze-bulb-test-kit/psbtk-zidPSBTK-product for an example, might need to build it outta pieces) There are different springs in those valves to determine the opening pressure, you may need to check its color & look in the manual to see what the corresponding pressure is. After that, get the numbers of all the various pieces, download the manuals, & start reading.

Something like this coming out of the ground is a lot of work, but once you've got a feel for it the next one will go easier!

EBEBRATT-Ed

What @ratio said is correct. If the air line to the valve has pressure the valve should open and close when the air line is removed and reconnected. It would be best to have a pressure gauge on on the air line going to the valve so you can see the pressure. Th valves do have different spring ranges, and the valve could be NO or NC. so you have a lot of things to sort out.

Jalen_Jalen2006

https://forum.heatinghelp.com/discussion/comment/1817632#Comment_1817632

there’s pressure everywhere. It’s never hot

Jalen_Jalen2006

I had a gauge inline and I have pressure I actuate the thermostat and there’s no pressure the valve doesn’t do anything. So that’s why I had diagnosed as bad but I’m second guessing myself as pneumatics is something I’m currently learning.

Jalen_Jalen2006

https://forum.heatinghelp.com/discussion/comment/1817665#Comment_1817665

I responded but didn’t press quote my bad

mattmia2

Sounds like a normally open valve and it is stuck closed. Or it is air bound.

ratio

You should be able to pull the actuator off the stem & see if the valve can be operated manually as well. It should move up & down by hand without too much effort (think of the spring that operates it).

I've repaired those valves by swapping out the top half out from a new one, too. Use a big box end (preferable) or a pipe wench to take it apart, gently rap on it to break the corrosion that's holding it together.

Air bound is always a possibility, too… Might check for that before you try to get that valve apart.

mattmia2

Since it looks like it is leaking the valve should be repaired either way.

pecmsg

heating valves should fail Open with no air.